Opioids are a class of drugs that include the illegal drug heroin and analgesics available legally by prescription, such as oxycodone (OxyContin®), hydrocodone (Vicodin®), codeine and morphine. Opioids are powerful pain relievers, but their use is hindered by tolerance to the analgesic effects, physical dependence resulting in withdrawal syndrome, and the possibility of addiction.
Dependence is characterized by physical or psychological withdrawal symptoms upon discontinuation of an opioid. Dependence may be independent of addiction. However, physical dependence, or the desire to avoid withdrawal symptoms, is thought to contribute to opioid addiction, particularly at later stages of addiction; whereas, a craving for the euphoric effects of opiates may dominate in earlier stages (Burns, L, Recent Developments in Pain Research, 11-136 (2005)). The somatic withdrawal signs that can occur when opioid therapy is abruptly stopped in physically dependent individuals include agitation, irritability, muscular ailments, abdominal pain, diarrhea, burning sensations, “gooseflesh,” and itching. In an effort to minimize withdrawal symptoms, patients are required to be carefully tapered off of the opioid. However, such approach requires strict monitoring throughout an extended protocol.
Due to the potential dire consequences of opioid use, there is an urgent need to enable an efficient cessation of opioid use with minimal withdrawal symptoms.